1. Technical Field
The present invention relates to a liquid discharge apparatus, a head unit, a control unit, and a method for controlling the liquid discharge apparatus.
2. Related Art
An ink jet printer for printing images and documents by using a piezoelectric element (for example, piezo element) as a discharge unit that discharges liquid such as ink and the like, is known. The piezoelectric element is provided in a head unit so as to correspond to each of a plurality of nozzles, and configured to discharge a predetermined amount of ink (liquid) at predetermined timing from the nozzle by driving each of the plurality of nozzles according to a drive signal.
In this configuration, when the viscosity of ink is increased (thickened) within a discharge unit, abnormal discharge is generated, and the quality of images to be printed is reduced. In addition, when bubble is included in the ink within the discharge unit, abnormal discharge is generated, and similarly, the quality of image to be printed is reduced.
Accordingly, in order to realize high-quality printing, technology of detecting residual vibration generated after the piezoelectric element is driven, and of inspecting a discharge state of the ink by the discharge unit by analyzing a residual vibration signal indicating the residual vibration, is proposed (for example, see JP-A-2004-276544).
However, amplitude of the residual vibration is changed according to a usage situation and environment of a printer. Therefore, there is a case where a discharge state of ink by the discharge unit cannot be accurately determined due to an adverse effect in analysis of the residual vibration signal.